A virtual voltage injection-based speed sensor-less driving control method for induction motor, wherein in the method, based on an existing speed sensor-less drive system for induction motor, a virtual voltage injection module is added between stator voltage command input values usα and usβ and flux linkage observer stator voltage input values u*sα and u*sβ of a motor in an αβ coordinate system, or a virtual voltage injection module is added between stator voltage command input values usd and usq and flux linkage observer stator voltage input values u*sd and u*sq of the motor in a dq coordinate system, and the method comprises the following steps:
- S1. calculating k based on a parameter of an induction motor, wherein k is a proportional relationship in the virtual voltage injection module;
- S2. multiplying the stator voltage command input values usα and usβ of the motor in the αβ coordinate system by the proportional relationship k respectively to obtain the flux linkage observer stator voltage input values u*sα and u*sβ in the αβ coordinate system;
- or multiplying the stator voltage command input values usd and usq of the motor in the dq coordinate system by the proportional relationship k respectively to obtain the flux linkage observer stator voltage input values u*sd and u*sq in the dq coordinate system;
- the operation is equivalent to injecting usα_inj and usβ_inj on the basis of usβ and usβ, wherein usα_inj=(k−1)usαusβ_inj=(k−1)usβ to satisfy u*sα=usα_inj+usα=kusα, u*sβ=u*sβ_inj+u*sβ=kusβ,
- in the formula, usα_inj is a virtual voltage injection value under an α-axis,
- and usβ_inj is a virtual voltage injection value under a β-axis;
- or the operation is equivalent to injecting usd_inj and usq_inj on the basis of
- usd and usq, wherein usd_inj=(k−1) usdusq_inj=(k−1)usq to satisfy u*sd=usd_inj=usd=kusd, u*sq=usq_inj+u*sq=kusq,
- in the formula, usd_inj is a virtual voltage injection value under a d-axis, and
- usq_inj is a virtual voltage injection value under a q-axis;
- S3. constructing a dynamic mathematical model of a flux linkage observer based on u*sα and u*sβ or u*sd and u*sd;
- S4. observing an induction motor rotor speed {circumflex over (ω)}r using a rotating speed observer and observing a rotation angle θ of a rotor flux linkage using the flux linkage observer based on the dynamic mathematical model of the flux linkage observer:
- S5. implementing a control of speed sensor-less induction motor rotating speed and torque by using the observed rotor speed {circumflex over (ω)}r for a rotating speed PI adjustment module and the flux linkage observer and using the observed rotor flux linkage rotation angle θ for a 2-phase synchronous rotation coordinate/2-phase static coordinate conversion module;
- wherein the αβ coordinate system is a 2-phase static coordinate system and the dq coordinate system is a 2-phase synchronous rotation coordinate system;
- wherein step S5 comprises the following steps:
- S501, performing a rotating speed PI control after taking a difference with a corresponding rotating speed command ω*r using the observed induction motor rotor speed {circumflex over (ω)}r as a feedback value of the rotating speed PI adjustment module;
- S502, using the observed flux linkage rotation angle θ for a coordinate conversion calculation in a 2-phase synchronous rotation coordinate/2-phase static coordinate conversion module;
- S503, using an output i*sq of the rotating speed PI adjustment module as a command of a q-axis current PI adjustment module and using an output i*sd of a flux linkage current command given module as a command of a d-axis current PI adjustment module;
- inputting induction motor two-phase currents iU and iV obtained by sampling via a current sensor to a 3-phase static coordinate/2-phase static coordinate conversion module, and then outputting is to the 2-phase synchronous rotation coordinate/2-phase static coordinate conversion module, and lastly obtaining a d-axis current isd and a q-axis current isq in the 2-phase synchronous rotation coordinate system, and performing a current PI control after using the obtained d-axis current and q-axis current as feedback values of a d-axis current PI regulator and a q-axis current PI regulator respectively and taking a difference with corresponding flux linkage current commands i*sd and i*sq;
- S504, inputting outputs usd and usq of the d-axis and q-axis current PI adjustment modules to the 2-phase synchronous rotation coordinate/2-phase static coordinate conversion module, which converts a motor input voltage command in the 2-phase synchronous rotation coordinate system to a motor input voltage command us in the 2-phase static coordinate system;
- S505, outputting us to a voltage space vector pulse width modulation module to generate a switching signal for controlling switching devices SA,SB,SC, thereby achieving an object of controlling induction motor speed and torque.